Sex Steroids, Sleep, and Metabolic Dysfunction in Women (SCOR)

Increased plasma triglyceride concentration is a common feature of the metabolic abnormalities associated with obesity and a major risk factor for cardiovascular disease. Obesity is a major risk factor for two conditions that appear to be increasing in prevalence in women: the polycystic ovary syndrome (PCOS) and sleep disordered breathing. PCOS affects 5-8% of women. Sleep disordered breathing affects up to 10% of women. Obstructive sleep apnea (OSA) is the most common cause for sleep disordered breathing and particularly prevalent in obese women with PCOS (~50%). Both PCOS and OSA augment the increase in plasma triglyceride (TG) concentration associated with obesity, and the effects of PCOS and OSA on plasma TG concentration appear to be additive. The mechanisms responsible for the adverse effects on plasma TG metabolism are not known. The primary goal of this project, therefore, is to determine the mechanisms responsible for the increase in plasma TG concentration in obese women with PCOS and OSA. It is our general hypothesis that alterations in the hormonal milieu that are characteristic of these two conditions are, at least in part, responsible for the increase in plasma TG concentration in obese women with the conditions. Furthermore, we hypothesize that the hormonal aberrations characteristic of the two conditions are particularly harmful to obese, compared with lean, women. The effects of PCOS on skeletal muscle protein metabolism are also not known. However, sex hormones are thought to be important regulators of muscle protein turnover suggesting that muscle protein metabolism is likely to be affected by PCOS. We will examine this by determining the effect of individual sex hormones on muscle protein metabolism and hypothesize that testosterone administration will stimulate muscle protein metabolism while estrogen and progesterone administration will inhibit muscle protein metabolism.

Postmenopausal women - tested before and after no treatment. Duration between before and after testing ranged from 31 to 78 days with an average of 46 days between visits

Micronized progesterone, 100 mg/d vaginally. The intervention lasts 70 days in total and consisted of 14 days on treatment, 14 days off treatment, 14 days on treatment, 14 days off treatment and a final 14 days on treatment. Testing is performed before and at the end of the 70 day intervention.

Testosterone gel 1250 ug/d applied transdermally for a total of 21 days. Testing is performed before and at the end of the 21 day intervention.

Dexamethasone 0.013 mg/kg fat-free mass daily taken orally for a total of 21 days. Testing is performed before and at the end of the 21 day intervention.

Breathe through the mask of a continuous positive airway pressure device every night when sleep, for 6 weeks. Testing is performed before and at the end of the 6 week intervention.

Estrogen treatment (100 ug Estradiol daily) administered transdermally by using continuous delivery patches. The intervention lasted 70 days in total and consisted of 14 days on treatment, 14 days off treatment, 14 days on treatment, 14 days off treatment and a final 14 days on treatment.

VLDL was isolated from plasma by ultracentrifugation with the tracer-to-tracee (TTR) of free glycerol in plasma and glycerol in VLDL-TG determined by gas chromatography-mass spectrometry. The fractional turnover rates of VLDL-TG was determined by fitting the glycerol TTR time courses in plasma and in VLDL-TG to a multicompartmental model. The hepatic (liver) secretion rates of VLDL-TG was calculated by multiplying the fractional turnover rates of VLDL-TG by the of VLDL-TG concentration.

VLDL was isolated from plasma by ultracentrifugation with VLDL-TG concentration measured by using a colorimetric enzymatic kit (Sigma-Aldrich, St. Louis, MO).

VLDL was isolated from plasma by ultracentrifugation with the tracer-to-tracee (TTR) of free glycerol in plasma and glycerol in VLDL-TG determined by gas chromatography-mass spectrometry. The fractional turnover rates of VLDL-TG was determined by fitting the glycerol TTR time courses in plasma and in VLDL-TG to a multicompartmental model. The plasma clearance rate of VLDL-TG was calculated by dividing the VLDL-TG secretion rate by the VLDL-TG concentration.

VLDL was isolated from plasma by ultracentrifugation with the tracer-to-tracee (TTR) of free glycerol in plasma and glycerol in VLDL-TG determined by gas chromatography-mass spectrometry. The fractional turnover rates of VLDL-TG was determined by fitting the glycerol TTR time courses in plasma and in VLDL-TG to a multicompartmental model. The plasma clearance rate of VLDL-TG was calculated by dividing the VLDL-TG secretion rate by the VLDL-TG concentration.

The fractional synthesis rate (FSR) of muscle protein synthesis was determined by assessing the incorporation of [5,5,5-2H3]leucine into muscle proteins. [5,5,5-2H3]leucine was infused for 5 hours with muscle biopsies obtained from the vastus lateralis muscle in the thigh 2 and 5 hours. The leucine tracer-to-tracee ratio (TTR) in muscle protein and the muscle free leucine pool was determined by gas chromatography-mass spectrometry (GCMS) and the FSR of muscle proteins calculated using a standard precursor-product model. The FSR was calculated as %/h, which reflects the percent of all proteins in the muscle that were synthesized (made) per hour.

Inclusion Criteria: Women aged 18-75 years and men 45-75 years Healthy lean, overweight and obese women (BMI 18-40 kg/m2) and obese men (BMI 30-40 kg/m2) Obese women (BMI 30-40 kg/m2) with OSA or PCOS Exclusion Criteria: Pregnant, lactating, peri- or postmenopausal women will be excluded from the study because of potential confounding influences of these factors and potential ethical concerns (pregnant women) Women taking medications known to affect substrate metabolism and those with evidence of significant organ dysfunction (e.g. impaired glucose tolerance, diabetes mellitus, liver disease, hypo- or hyper-thyroidism) other than PCOS and OSA Severe hypertriglyceridemia (fasting plasma TG concentration >400 mg/dl) Subjects with OSA who have an apnea-hypopnea index (AHI) score >30 (the total number of obstructive events divided by the total hours of sleep) will be excluded and instructed to seek medical care

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Wang X, Smith GI, Patterson BW, Reeds DN, Kampelman J, Magkos F, Mittendorfer B. Testosterone increases the muscle protein synthesis rate but does not affect very-low-density lipoprotein metabolism in obese premenopausal women. Am J Physiol Endocrinol Metab. 2012 Mar 15;302(6):E740-6. doi: 10.1152/ajpendo.00533.2011. Epub 2012 Jan 17.

Smith GI, Reeds DN, Okunade AL, Patterson BW, Mittendorfer B. Systemic delivery of estradiol, but not testosterone or progesterone, alters very low density lipoprotein-triglyceride kinetics in postmenopausal women. J Clin Endocrinol Metab. 2014 Jul;99(7):E1306-10. doi: 10.1210/jc.2013-4470. Epub 2014 Apr 2.

Smith GI, Yoshino J, Reeds DN, Bradley D, Burrows RE, Heisey HD, Moseley AC, Mittendorfer B. Testosterone and progesterone, but not estradiol, stimulate muscle protein synthesis in postmenopausal women. J Clin Endocrinol Metab. 2014 Jan;99(1):256-65. doi: 10.1210/jc.2013-2835. Epub 2013 Dec 20.